ORGANIZATION OF SLEEP AND WAKEFULNESS AFTER MATERNAL SEPARATION IN YOUNG-RATS

Two-week-olf infant rats were studied before and after 24 h of maternal absence. This experience produced an increase in time spent awake, a reduction in time spent in paradoxical sleep (PS), and an increased frequency of state transitions with more frequent and shorter periods of both slow-wave sleep (SWS) and PS. Body movements were increased and nonnutritive sucking decreased during PS after separation. Other aspects of sleep organization were relatively stable: the pattern of probability of direction of state transitions, the integration of the physiological and behavioral determinants of state, the pattern and amount of nonnutritive sucking, and the underlying PS cycle period. Some aspects of the prolonged absence of the mother may produce a shift in the infant''s central neutral state regulation through processes yet to be understood.